Iceland volcanoes have been Jay Miller's a topic of study for the last 25 years. If history is any indication, the erupting volcano in Iceland and its immense ash plume could intensify, he says.

Jay Miller, a research scientist at Texas A&M University who has made numerous trips to the region, says the ash produced from Iceland volcanoes can be deadly, which is why hundreds of flights from Europe have been canceled for fear of engine trouble.

"What happens is that the magma from the volcano is around 1,200 degrees and it hits the water there, which is near freezing," he explains. "What is produced is a fine ash that actually has small pieces of glass in it, and it can very easily clog up a jet engine. If you were to inhale that ash, it would literally tear up your lungs."

Miller says most volcanoes in Iceland erupt only about every five years on average and are relatively mild, but history is repeating itself. Extremely large eruptions occurred there in 934 A.D. and again in 1783 that covered Europe with ash much like today.

"Ben Franklin was ambassador to France in 1783 and he personally witnessed the large ash clouds over Europe, and he later wrote that it was a year in which there was no summer," Miller adds. "The big question now is, what happens next? It's very possible this eruption could last for quite some time, but no one knows for sure. Volcanoes in that part of the world are very hard to predict."